for循环

for循环的用法是：

for (初始条件; 循环检测条件; 循环后更新计数器) {
// 执行语句
}

		要对一个整型数组的所有元素求和，可以用for循环实现：
// for
public class Main {
  public static void main(String[] args) {
    int[] ns = { 1, 4, 9, 16, 25 };
    int sum = 0;
    for (int i=0; i<ns.length; i++) {
        System.out.println("i = " + i + ", ns[i] = " + ns[i]);
        sum = sum + ns[i];
    }
    System.out.println("sum = " + sum);
}}

for each循环

更简单地遍历数组：

// for each
public class Main {
public static void main(String[] args) {
    int[] ns = { 1, 4, 9, 16, 25 };
    for (int n : ns) {
        System.out.println(n);
    }
}}